How are gorges formed?

Gorges, also called 'revines', or 'flumes', or  'canyons ' are deep, narrow valley with sharply steep cliff. Thy are formed mostly due to the action of flowing water when a stream or a river digs into the surrounding rocks. The most famous Gorges is the Grand  canyon in the USA, Arizona;it is almost 1800mdeep in places. Over a period of 600million years, the Colorado River carved the Grand canyon by eroding the surface of the Colorado plateaus, which are to a large  extent made-up of sandstone and argillite.